I started my 4th game tonight and everything was going great. Until around turn 30. Always turn 30.

The game start was a challenge, I had trouble finding a region with anything in it. Mostly desert, but no resources. Finally I find a region, and beside it is another region. I plop an outpost, go up an era, get my city and plop an outpost. It finishes, and I link them. A few turns later I bump into Poe. We start a trade deal for luxuries and than everything. Speeding right along we go for non-aggression pact! here I am thinking things are getting pretty serious, maybe even an alliance?

And then out of no where he demands my outpost, the one I have linked too my capital. It's not bordering his land (well until he plopped his land down a turn before) and it's got like, one luxury resource on it, compared to his which all have 2 or 3. I say no.

War. He just straight up declares war on me. We we're pleasant with each other, lots of agreements and all because he can't have my one region he goes to war. Why? He was introverted and Wary, not militaristic. And I know what you're thinking, and no, I'm playing on Big City (3rd difficulty) I'm not even playing on a hard difficulty. I wasn't in his borders, I always just let his skirmishes go. I never demanded anything and just... instantly war.

I don't understand why. This is the 4th time this has happened to me in a row, things are going good until the AI out of no where declares war for some stupid ass reason. I'd get it if there was more reasoning, like I kept building right on his border, or I kept crossing into his cities, but we had a really good standing, all for a city that was there before he even showed up at my door. I'd get it if I was running a high difficulty game like 5th or higher but I'm running on the 3rd difficulty focusing away on science and trying to not let my people not starve.